Question

A survey of several 8 to 9 year olds recorded the following amounts spent on a trip to the mall: $31.11,$25.01,$18.53,$14.37,$24.16,$21.91 Construct the 80% confidence interval for the average amount spent by 8 to 9 year olds on a trip to the mall. Assume the population is approximately normal. Step 1 of 4 : Calculate the sample mean for the given sample data. Round your answer to two decimal places.

Answer 1

Solution :

Amounts spent on a trip : $31.11, $25.01, $18.53, $14.37, $24.16, $21.91

Confidence interval = 80%

Average amount spent = 8 to 9 years old

One sample T confidence interval

μ : Mean of variance

80% of confidence interval results :

Using statistical software,

Variable : data

Sample mean : 22.515

Std. Err. = 2.3479945

DF = 5

L. limit : 19.049632

U. Limit : 25.980368

SD = 5.75

Critical value = 1.476